Abstract
State of plankton community was monitored in the Pacific waters at Kuril Islands in July-August 2016, in conditions of mass feeding migrations of subtropical fish. Structure of the plankton community corresponded to its summer season: the large-sized fraction of zooplankton prevailed by biomass (74-86 %), the portions of medium- and small-sized fractions were 3-13 % and 11-15 %, respectively. The dominant groups in the large-sized fraction were copepods ( Neocalanus plumchrus, Metridia okhotensis, Metridia pacifica, Eucalanus bungii ), arrowworms ( Sagitta elegans ) and hyperiids ( Themisto pacifica ). Copepoda nauplii and copepodites of I-II stage, Euphausiacea furcilia and caliphyptophytes, and juvenile hyperiids were found in the small-sized and medium-sized fractions. Total biomass of the large-sized fraction was significantly higher in summer 2016 than in July-August 2015, obviously because of earlier phase of seasonal succession under colder thermal regime. In 2016, the biomasses of copepods and sagittas were at the mean long-term levels, and the biomass of euphausiids was above the norm. The biomasses of the small- and medium-sized fractions were above the norm, too. The total stock of plankton in the surveyed area in July-August 2016 was assessed in 92926 . 10 3 t. High biomass of zooplankton in this area was favorable for feeding of subtropical fish.
Highlights
State of plankton community was monitored in the Pacific waters at Kuril Islands in July-August 2016, in conditions of mass feeding migrations of subtropical fish
Structure of the plankton community corresponded to its summer season: the large-sized fraction of zooplankton prevailed by biomass (74–86 %), the portions of medium- and small-sized fractions were 3–13 % and 11–15 %, respectively
In 2016, the biomasses of copepods and sagittas were at the mean long-term levels, and the biomass of euphausiids was above the norm
Summary
В июле-августе 2016 г. в прикурильских водах Тихого океана был проведен мониторинг состояния планктонного сообщества в связи с возобновлением массовых нагульных миграций субтропических рыб. В прикурильских водах Тихого океана был проведен мониторинг состояния планктонного сообщества в связи с возобновлением массовых нагульных миграций субтропических рыб. Доминирующими группами в крупной фракции зоопланктона были копеподы (Neocalanus plumchrus, Metridia okhotensis, Metridia pacifica, Eucalanus bungii), сагитты (Sagitta elegans) и гиперииды (Themisto pacifica). State of plankton community was monitored in the Pacific waters at Kuril Islands in July-August 2016, in conditions of mass feeding migrations of subtropical fish. The dominant groups in the large-sized fraction were copepods (Neocalanus plumchrus, Metridia okhotensis, Metridia pacifica, Eucalanus bungii), arrowworms (Sagitta elegans) and hyperiids (Themisto pacifica). Цель работы — анализ состояния планктонного сообщества как кормовой базы в связи с возобновлением массовых нагульных миграций субтропических рыб в прикурильские воды. Экспедицией на НИС «ТИНРО» были проведены сборы зоопланктона для определения биомассы и структуры планктонных сообществ. 1. Схема расположения планктонных станций в северо-западной части Тихого океана в июле-августе 2016 г. Для мелкой фракции приняли коэффициент [1,5]; для средней фракции — 2,0; для планктона крупной фракции применялись группоспецифические поправки: для эвфаузиид, мизид и щетинкочелюстных длиной до 10 мм — 2,0, 10–20 мм — 5,0, более 20 мм — 10,0; для гипериид длиной до 5 мм — 1,5, 5–10 мм — 3,0, более 10 мм — 5,0; для копепод длиной до 5 мм — 2,0, более 5 мм — 3,0; для полихет, мелких медуз, птеропод и других малоподвижных животных — 1 (Рекомендации..., 1984)
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